Data storage systems are used to store information provided by one or more host computer systems. Such data storage systems receive requests to write information to a plurality of data storage devices, and requests to retrieve information from that plurality of data storage devices. It is known in the art to configure the plurality of data storage devices into two or more storage arrays.
Storage system vendors have begun providing the availability of high-capacity, low-cost storage class devices (near-line class storage devices such as serial-advanced technology attachment (SATA) and fibre channel advanced technology attachment (FATA) which typically have lower reliability characteristics than the more traditional server class devices (FC-AL, SCSI, SAS, SSA) with larger capacity per device. When such devices are intermixed within a data storage system, it may result in an intermix of storage device technologies that have differing reliability characteristics within the same global sparing domain.
When these devices are intermixed within the same global sparing domain, it is possible that even in systems that disallow intermix of storage technology classes during array creation due to storage devices failures a RAID array will contain devices of an intermix of storage technology classes. The operation of a RAID array with an intermix of storage device technology classes can be problematic due to the difference in reliability characteristics of the devices. The difference in the Mean Time Between Failure (MTBF) and performance (resulting data transfer rates of a device in different IO workloads) between the storage device technology classes may result in array performance degradation and/or increased exposure to data loss from subsequent storage device failures.
What is needed is an apparatus and method to reconfigure one or more of the storage arrays when an unassigned data storage device is detected in the data storage system. Additionally, what is needed is a method of reconfiguration providing a policy that establishes a priority to restoring the reliability of a RAID array to optimum during a repair action where an eligible storage device has been repaired.